1. Field of the Invention
The present invention is directed to a chain switching device, and in particular for sprockets on the pedal bearing of a frame for a bicycle.
2. Description of the Related Art
U.S. Pat. No. 4,330,137 discloses an arrangement of a chain switching device on the frame of a bicycle which has a cage for guiding and for switching a bicycle chain, wherein the cage is arranged on a parallel guide device connected with the frame by means of a fastening part. As described in the patent, the fastening part is not fastened to the seat tube as is customary, but rather is fastened to the pedal bearing housing, wherein any position of the cage relative to the chain can be achieved by rotating the fastening part. Because of the design of the cage, optimum alignment of the adjusting ring of the cage to the pull portion or traction portion of the chain running on the sprockets is required. Exact alignment is made possible by swiveling the fastening part that is rotatably fastened to the pedal bearing. Defect-free operation is realized in this manner, however, at the expense of a relatively complex construction of the chain switching device that is only mountable on frames having a specially designed pedal bearing housing adapted to the new mounting conditions of the fastening part of the chain switching device. Thus, it is possible to mount this chain switching device only in frames which are designed during manufacture for the mounting of the chain switching device.
It is therefore the object of the invention to provide a chain switching device for a chain such that a plurality of chain switching devices can be produced with a constant number of parts. In addition, it is desirable to develop chain switching devices which can be mounted in each instance at the seat tube in an angular area relative to the chain that is optimum for operation at a variety of angles between a seat tube at which this chain switching device is mounted and a chain brace whose position relative to the chain remains constant regardless of the frame construction.